1. Field of the Invention
This invention relates generally to a system and process for fluorometrically quantifying potentially mineralizable nitrogen for agricultural crop production, and in particular to a process of soil analysis for measuring potentially mineralizable nitrogen and calibration of the soil-based nitrogen process to allow for site or field specific management of nitrogen fertilizers.
2. Description of the Related Art
For field crops within the United States there is currently no analytical method used on a state or regional basis that can consistently and accurately predict the amount of soil nitrogen mineralized during a cropping season, and in turn the nitrogen fertilizer needs required for achieving optimum yields on a site-specific or year to year basis. Current nitrogen fertilizer recommendations for rice, wheat, corn, grain sorghum and cotton in the U.S. are typically based on soil texture, variety, yield goal and/or the previous crop grown. This approach often will maximize yields, but in many cases leads to over-fertilization with nitrogen resulting in increased lodging potential as well as requiring additional input costs in the form of fungicides to reduce disease pressure.
As such, management of fertilizer nitrogen is a critical component for producing consistent crop yields, as nitrogen fertilizer represents a considerable input cost and has serious environmental consequences if over applied. For example, nitrogen fertilizer costs represent anywhere from 20-30% of a producer's total input expenditures for rice produced on silt loam soils. The prevalence of nitrogen in the cells of agronomic crops means that harvest removes large quantities of nitrogen from a field, and, in doing so, creates a paucity of the nutrient residual in the soil for future production. This, coupled with nitrogen loss from soils by leaching, volatilization and denitrification, establishes a situation in which nitrogen is the nutritional factor most commonly limiting crop yield potential. To remedy this, plant-available nitrogen forms are provided to the crop in the form of chemical fertilizers, such as anhydrous ammonia and urea. Synthetic nitrogen fertilization is a cornerstone of modern agriculture because it provides the nutrients needed for elevated grain yield and quality. Therefore, it is important to apply the correct amount of fertilizer to meet the crop's need but not to supply more than is required because of the cost and environmental concerns.
The diagnosis of in-season nitrogen deficiencies must be followed by corrective nitrogen applications to recover potential yield. A key to corrective nitrogen fertilization action is up-to-date knowledge of advent and degree of nitrogen deficiency. Immediate knowledge of plant nitrogen concentration is often not obtainable due to a lag time for processing. This lag time can negatively affect the value of the derived information due to the short window during which nitrogen demand is increasing and deficiencies can be most effectively corrected.
There are few tools that are currently available to help farmers determine if crop nitrogen levels during the season are adequate, and several techniques have been used to objectively measure crop color, including reflectance measurements, chlorophyll and amino acid analysis. Reflectance, chlorophyll, and amino acid measurements all require relatively expensive equipment, and transport of samples to a laboratory for analysis. Shipping these materials to a qualified testing service can compromise the brief window in which the information might be of value.
It is therefore desirable to provide a system and process for fluorometrically quantifying potentially mineralizable nitrogen for agricultural crop production.
It is further desirable to provide a process soil analysis for measuring potentially mineralizable nitrogen and calibration of the soil-based nitrogen process to allow for site or field specific management of nitrogen fertilizers.
It is yet further desirable to provide a soil analysis process that allows producers to utilize field-specific nitrogen rates rather than applying blanket recommendations based on rice variety, soil texture, and previous crop.
It is still further desirable to provide a system and process for fluorometrically quantifying potentially mineralizable nitrogen for agricultural crop production that is automated, faster, less laborious, uses less caustic chemicals and is more apt to be used in mainstream soil test laboratories and adapted on a wide scale than prior methods.
It is yet further desirable to provide an automated fluorometric soil analysis system and process that provides savings due to a reduction in nitrogen fertilizer needs, while still maximizing yields, and savings in fungicide costs due to less disease incidence and/or severity of disease.
It is still further desirable to provide a system and process for fluorometrically quantifying potentially mineralizable nitrogen for agricultural crop production that increases yield due to a reduction in the incidences and severity of lodging, and that increases earnings from increased yields on fields that have unknowingly been under fertilized with nitrogen fertilizer.